Air, gas, or smoke extractor



1934- I D. F. MACDONALD 1,968,949

AIR, GAS, OR SMOKE EXTRACTOR Filed June 30. 1932 Patented Aug. 7, 1934 PATENT OFFICE 1,968,949" nt, GAS, on \SMOKE' nxTRAo'roR Duncan Finlaysori Macdonald, Kim, Argyll',

. Scotland Application June 30, 1932, Serial No. 620,135 7 In Great BritainJuly 15, 1931- 4 Claims. (Cl."98 -20)" Q 1 This invention relates to an improved extractor whereby air, gases or smoke canbe extracted from thevcompartm'ents of road orrailway vehicles, the rooms of buildings, the. cabins or interior spaces Q 5 of ships or other places, and forapplication to domestic-or industrial smoke-stacks.

According to the invention, 1' provide, an air, gas or smoke extractor comprising a cover or innernmember which is either continuous right :I round the extractor or faces in at least three, or preferably. more, directions, and which is surroundedatall sides by an outer deflecting or wall member, the coveror inner member being supported above a hollow shaft through which air I isto 'be extracted and the outer surrounding member being arranged in such spaced overlapping relationship to the cover or inner member that-Wind or air currents blowing from any direction across the inner and outer'members effect 1 the extraction or aspiration of air, gas or smoke from the hollow shaft through the space'between the members.

In-my improved air, gas or smoke extracton: the inner member or cover preferably depends in Sfspace'd overlapping relationship over the hollow central 'air shaft, whilst overlapping parts of the.

inner. and outer members may-.be partly inclined to the vertical.

The inner. cover may comprise a three sided iorvother pyramid, or a cone, pyramidal or conicalfrustum, ora hemisphere, and be freely exposed to the outer air or wind currents. The outer surrounding member may be constituted by a trustee conical ring or'other hollow tapered orcylindrical l-ishell.

According to a further feat ure of the invention, my improved extractor is provided with means whereby inward draughts, occasioned by external inward air currents or otherwise, are v"prevented from being transmitted through, or produced in, the passage or opening whereby the extractor communicates with a chimney, fire grate or other interior space from which smoke or the like is to be extracted. The inward ,idraught preventer may comprise an external shield or baflie, or a deflecting surface or surfaces provided or formed on the inner member or cover of the extractor.

Several embodiments of the invention will now be described, by way of example, with reference to the annexed drawing, in which:-

Fig. 1 is a sectional elevation of one form of air extractor according to the invention; Fig. 2 is a sectional elevation of another circular extractor according to the invention.

or wholly Referring to the drawing,

Referring to Figs. 1 and 2:-.- The extractor has the air shaft 1 communicating with the interior of the space to be ventilated. The inner member of the extractor is constituted byacowl 2 of spherical shape having a depending cylindrical skirt 3. This skirt extends. between the: air shaft 1 and an outer frusto conical ring 4 which is spaced away from the skirt 3 of the :cowl 2 and is mounted on a base plate v5 extending inwardlyto the air shaft 1.

Between the outer ring 4 and the cowl 2 a continuous annular air belt 8 is'provided and a con tinuous annularair belt '7 is also provided between thecowlz and the shaft 1. The cowl 2 is supported by a central rod 9 carried by a diametrical bridge 10 in the upper end of the shaft 1, and is steadied by brackets 12.which.may be secured to the base plate 5.

The inner. and outer members 2, 'present exterior surfaces which like the air belts 7 and 8' are continuous right round the extractor. As a consequence ofthesetwo features, there is, firstly, no airspace which is not available for the extraction of air, and, secondly, the inner and outer members 2, 4 functionso as to effect the extraction or aspiration'of' the air up through the central air shaft 1 in respect of external air cur-: rents from any angle or direction within a compassof 360.

As "will also'be apparent, the cowl2, 3 can be readily lifted out of thereceptacle formed by the outer ring or deflecting member 4 and the base plateb bymerely're'moving one of the nuts holding the cowl'on the central rod 9. Hence the" whole of the extractor is readily accessible for either inspection or cleaning.

,in the extractor is eliminated and the extractor efficiency increased. In the extractor shown in Fig. 2, also, an external shield 13 is mounted on top of the central rod 9 so as to extend over the gap between the top edge of the outer ring 4 and the peripheral part of the cowl 2, 3. The shield 13 acts both as a bafiie to prevent inward currents through the said gap into the shaft 1 and as a plate to constitute an annular gap 13a, 1. e. between the outer edge of the shield 13 and top edge of the ring 4.

As a result of this arrangement, winds blowing head-on against the shield 13 exert an inductive action at the annular gap 13a and air, gas or smoke is thereby induced up through the shaft 1.

In this manner, the construction shown in Fig. 2 acts as an extractor whether the external winds are blowing in the plane of the extractor or'head on against the same, or from any intermediate direction, which feature is particularly advantageous when the extractor ls fitted to a vent or opening with its axis horizontal (instead of vertical as in Fig. 2). w

It will be understood that whilst the extractors shown in the drawing are generallymade of metal, the extractor may also be made of fireclay and may be adapted for use as a smoke extractor or chimney can, or as an adjunct thereto.

At any one or more places round the outer wallmember or ring, and/or nearv the top'of the inner member or cowl, an opening provided with a hinged or sliding door may be made so as to allow for examination of the interior of the extractor. The inner and outer members may also, if desired, be provided with inclined or curved ribs so arranged that they assist the flow of wind currents upwards and over the outlet spaces of the said member, in order to increase the extractor effect.

It will be apparent from the drawing that the central rod by which the dome or inner member of each extractor is supported may be dispensed with and the dome or inner member supported by three or more small rods whichdepend from its periphery and are secured to the base plate of the extractor by screw nuts.

Another modification which may be made in the extractor consists in providing webs or partitions extending radially or otherwise between the inner and outer members. They can be used to prevent any swirling of the air or the like round the space between the members. Moreover, where such webs or partitions are used they may serve as the sole or partial means of support of the inner member or cover, e. g. the central rod 9, Figs. 1 and 2 may be dispensed with when webs are used.

While the invention is applicable to extractors for air, smoke or other gases, the extractor will be referred to for convenience in the following claims simply as an air extractor.

I claim:

1. An air extractor comprising a tubular shaft, a laterally extending flange plate connected therewith, a frusto conical ring connected at its base with the outer periphery of said flange plate, a hood shaped member extending over the upper end of said tubular shaft and spaced from the interior wall of said frusto conical ring, a deflecting plate disposed over said hood shaped member and means for detachably mounting said hood shaped member and said deflecting plate with respect to said tubular shaft, said deflecting plate extending beyond the limits of said frusto conical ring and said hood shaped member having a deflecting surface extending at an acute angle with respect to the plane of said deflecting plate.

2. An air extractor comprising a tubular shaft, a flat plate projecting from said shaft in a position displaced from the end thereof, a ring member in the shape of an inverted conical frustum connected to the periphery of said plate with the larger diameter of the ring member terminating below the plane of the end of said shaft, 2, frusto conical ring member having the end thereof connected with the periphery of said inverted conical frustum ring member and extending beyond the end of said shaft with the walls of each of said ring members spaced from said shaft, a hood removably supported adjacent the end of said shaft and spaced from both said shaft and said ring members, and a deflecting plate supported over said hood.

3. An air extractor comprising a tubular shaft, a laterally extending flange plate connected there with, a pair of frusto conical ring members, one of the frusto conical ring members being connected at substantially the smallest diametrical section thereof with the outer periphery of said flange plate, the other of said ring members having the largest diametrical section thereof connected to the largest diametrical section of said first mentioned frusto conical ring member with the smallest diametrical section thereof terminating in spaced relation to the upper end of said tubular shaft, and a laterally extending-hood dis-.

posed in spaced relation to the end of said shaft and to the peripheral edge of said last mentioned frusto conical ring member.

4. An air extractor comprising a tubular shaft, a laterally extending flange plate connected therewith, a hood having a downwardly inclined head extending across said shaft, an annular skirt depending in spaced relationship over said shaft from the periphery of said head, and a pair of frusto-conical ring members one of which is connected intermediate its ends with the outer periphery of said flange plate, and connected at its top to the other frusto conical ring member.

DUNCAN FINLAYSON MACDONALD. 

